1. Field of the Invention
This invention generally relates to hermetically sealed cans with a removable can end panel for easy opening, and more particularly relates to a stackable, hermetically sealed, easy opening food product can with a removable pull-tab panel that may also be opened with a conventional can opener.
2. Description of Related Art
The ease with which food containers may be opened, and the strength and structural integrity of such containers in preserving freshness and flavor of the contents are significant factors to consumers and the canned food industry alike. The common "sanitary", hermetically sealed can has a design which is structurally suited for stacking, shipping and handling, but typically must be opened with a conventional can opener. The can lid is generally secured to the body of the can with a double or "chime" seam of a standard height and width to accept a standard can opener for cutting through the lid to open the can. With the advent of cans with removable can lid seams which could be opened with a key provided with the can, and removable pull tab panels, the consumer was freed from the necessity of using a separate can opener device for opening such food cans. Unfortunately, the configuration of the seams of such specialized cans often prevented opening of the cans with standard can openers.
The so-called "easy opening" cans have a lid with a scoreline of reduced thickness to define a removable panel, and have a pull tab or handle attached to the panel for tearing at least a part of the panel free from the can. However, the scorelines of such full panel, easy open cans have a tendency to fracture during shipping, especially when such cans are stacked one upon the other so that the weight of the stacked cans may exert considerable force to break the scoreline of a can lid.
In order to reduce some of the stresses on the scored can end panels during shipping, the "raised panel" design illustrated in FIGS. 1-3 was developed, in which a U-shaped trough was formed in the panel between the seam and the scored portion of the panel to allow the panel to flex, in order to cushion the panel against shocks that occur during shipping and handling. However, the existence of a trough around the inside of the seam of the lid prevents opening of the can with a conventional can opener. Since it is often difficult for individuals such as the aged or the infirm to open the pull tab, full panel cans, manufacturers frequently make both the easy-open type of can and the "sanitary" type of can for the same food products. It would therefore be desirable to provide an easy-open type of can which would withstand the rigors of stacking, shipping, and handling, and which can also be opened with a conventional can opener.
In addition, the thickness and configuration of an easy-open can lid is important for preventing the scoreline from fracturing due to the heat and pressures which develop within the can during sterilization of the processed foods stored in the can. It would therefore also be desirable to provide an easy open can lid with a configuration with improved strength which would allow the scoreline to withstand internal pressures during canning procedures, which would allow reduction of the thickness and diameter of the sheet metal used in forming the can lid, and reduction in the thickness of the scoreline to facilitate easier opening of the full panel, pull tab can lid.